The University of Kiel cosmic ray experiment on board Helios 1 measures nucleons above 1. 7 MeV/nucleon and electrons above 0.3 MeV in the inner solar system between 1.0 and 0.3 AU from the Sun. A first survey is given on quiet time proton and Helium spectra which are compared near Earth and close to perihelion. The anomalous Helium component is also present at radial distances within 0.4 AU. Quiet time Helium spectra from 3.8 to 48 MeV/nucleon gradually increase between December 1974 and June 1975. For the integral radial gradient (protons above 51 MeV) we estimate a value of (11±2.5) %/AU during a period of slowly increasing cosmic ray intensity. We discuss solar particle events on January 5 (at 0.93 AU), March 7 (at 0.41 AU), and March 19, 1975 (at 0.32 AU). The March 19 event was measured closer to the Sun than any other event before. It exhibits sharp temporal structures, differences in the time profiles of various particle species, and a large abundance of Helium 3, with a 3He/4He ratio of 2 to 3 in the range 5 to 7 MeV/nucleon. This event occurred close to the peak of a high speed solar wind stream.
ARK: https://n2t.net/ark:/88439/y032443
Permalink: https://geophysicsjournal.com/article/183
 
